Envelope tracking is a technique by which the bias or supply voltage (e.g., VCC) and current of a power amplifier (PA) in a transmit chain of a transmitter is controlled based on the RF signal envelope of the transmit signal being amplified by the power amplifier. The idea is to operate the power amplifier close to or slightly in compression and to lower the PA supply voltage when the instantaneous signal amplitude is low, thereby boosting the efficiency of the power amplifier and its supply generation.